Concrete block



FIG. 1 is a top perspective view of a concrete block showing my new design;

FIG. 2 is an end elevational view thereof;

FIG. 3 is an opposite end elevational view thereof;

FIG. 4 is a side elevational view thereof, the opposite side being a mirror image thereof;

FIG. 5 is a top plan view thereof; and

FIG. 6 is a bottom plan view thereof. 

The ornamental design for a concrete block, as shown and described. 